The present invention relates to an optical amplifier, light source module and optical system.
In general, the optical amplifier can amplify optical signals by using optical fibers doped with a rare-earth element such as erbium (Er), without light-electricity conversion.
FIG. 10 is a block diagram of an optical amplifier FA2 constructed according to the prior art. As shown in this figure, the optical amplifier FA2 has a pumping light source 1 configured to output a pumped light and an amplifier unit 3 configured to receive the pumped light from the pumping light source 1 through a first optical fiber 2 and amplify and output the optical signal inputted into the first optical fiber 2.
The pumping light source 1 may be in the form of a semiconductor laser module (LD module) and designed to output a pumped light of 980 nm band, for example.
The first optical fiber 2 may be in the form of an optical fiber doped with erbium (Er), for example, when an optical signal of 1550 nm band is to be amplified.
The amplifier 3 comprises an input terminal 4 configured to receive the optical signal, an output terminal 5 configured to output the amplified optical signal, first and second isolators 6, 7 configured to propagate the optical signal only in a direction from the input terminal 4 to the output terminal 5 while preventing the optical signal from transmitting in the opposite direction, and an optical multiplexer 8 which may be in the form of an optical coupler for multiplexing the optical light transmitting through the first optical fiber 2 with the pumped light supplied from the pumping light source 1 through the second optical fiber 9.
The optical signal from the input terminal 4 is inputted into the optical multiplexer 8 through the first optical fiber via the first isolator 6. On the other hand, the pumping light from the pumping light source 1 is inputted into the optical fiber 2 through the second optical fiber 9 and optical multiplexer 8.
The optical fiber 2 is pumped by the inputted pumping light to amplify the optical signal which is in turn outputted from the output terminal 5 through the optical multiplexer 8 and second isolator 7.
An optical amplifier of the present invention comprises a pumping light source configured to output a pumping light, an amplifier unit configured to receive the pumping light from said pumping light source and amplify an optical signal that passes therethrough, and an optical fiber disposed between said pumping light source and said amplifier unit, said optical fiber including an optical filter that is configured to attenuate the optical signal from said amplifier unit.
A light source module of the present invention comprises a light source configured to output a laser beam, an optical fiber configured to have said laser beam propagate therethrough, and an optical filter disposed in said optical fiber and configured to attenuate light having a first wavelength band that is different from a second wavelength band in said laser beam.
An optical system of the present invention comprises a first optical device configured to emit a light having a first wavelength band, a second optical device configured to emit a light having a second wavelength band, means for connecting said first and second optical devices, and an optical part configured to propagate the light having the second wavelength band from said second optical device to said first optical device through said connecting means, said optical part being configured to prevent the light having the first wavelength band from said first optical device to enter said second optical device through said connecting means and also to return from said connecting means or said second optical device back to said first optical device.
A method for generating pump light for an optical amplifier of the present invention comprises steps of;
emitting a light in a first optical bandwidth from a first optical device;
emitting another light in a second optical bandwidth from a second optical device;
passing the another light through a connecting portion from said first optical device to said second optical device, including sub-steps of,
preventing light in the first optical bandwidth from said first optical device from entering said second optical device, and also returning to said first optical device from at least one of said second optical device and the connecting portion.
A light source for an optical amplifier of the present invention comprises means for emitting a light in a first optical bandwidth, means for emitting another light in a second optical bandwidth, means for passing the another light to said means for emitting a light, including, means for preventing light in said first optical bandwidth from entering said means for emitting the another light, and also returning to said means for emitting a light from at least one of said means for emitting the another light and said means for passing.